jquery選擇器使用優化

1.避免包含 jQuery extensions

  jQuery extensions會只用本地的querySelectorAll()

// Slower (the zero-based :even selector is a jQuery extension)
$( "#my-table tr:even" );
 
// Better, though not exactly equivalent
$( "#my-table tr:nth-child(odd)" );

2.避免過分特性

$( ".data table.attendees td.gonzalez" );
 
// Better: Drop the middle if possible.
$( ".data td.gonzalez" );

3.儘可能使用id選擇器

// Fast:
$( "#container div.robotarm" );
 
// Super-fast:
$( "#container" ).find( "div.robotarm" );

4.避免通配符選擇

$( ".buttons > *" ); // Extremely expensive.
$( ".buttons" ).children(); // Much better.
 
$( ":radio" ); // Implied universal selection.
$( "*:radio" ); // Same thing, explicit now.
$( "input:radio" ); // Much better.